Electric-lighting apparatus.



No, 652,494. Patented June 26, i900.

C. A. TERRY.. ELECTRIC LIGHTING APPARATUS.

(Application filed July 14, 1898. Renewed Dec. 16, 1899.) (No Mgdal.)

. Prion.

CHARLES A. TERRY, on NEW YORK, N. Y.

ELECTRIC-LIGHTING APPARATUS.

SPECIFICATION forming part of Letters Patent No. 652,494, dated June 26, 1900.

Application filed July 14, 1898. Renewed December 16, 1899. $erial No. 740,607. (No model.)

T0 at whom it may concern:

Be it known that 1, CHARLES A. TERRY, a citizen of the United States of America, and a resident of New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Electrio-Lighting Apparatus, of which the follow ing is a specification.

My invention relates to certain improvements in the class of electric-lighting apparatus in which the illuminant or glower is composed of materials commonly known as conductors of the second class that is to say, materials which when in a conducting condition are believed to conduct current by electrolytic action. Such materials are usually termed non-conductors, as at ordinary temperatures they offer so great a resistance to the passage of electricity as to be practically insulators. When they are heated to a sufficient temperature,however, they become conductors and if subjected to a proper difference of potential currents will traverse them, which not only cause them to give 01f light, but under proper conditions maintain them in their heated conductive condition. The conductivity of this class of glowers, within certain limits, at least, increases with their temperature, so that in some instances it is necessary to provide means for checking an increase of current beyond predetermined limits; otherwise the increasing temperature due to increments of current might permit such an increasing flow of current that the glower would become destroyed by excessive heat. By placing a proper restraining device-such, for instance, as a resistance having a proper temperature coetticient in series with the glowera proper balance may be obtained, so that under the influence of a predetermined difference of potential a predetermined current will be caused to traverse the glower. In the case of alternating-current circuits eitheraresistance or a suitable reactive coil may be used.

The object of my invention is to utilize certain of the peculiar characteristics of this class of glowers to produce a lamp having a long life.

The invention involves an organization in which when the lamp is connected in circuit the current shall select a path through one or another of two or more glowers and con tinue to operate that glower until either the current is withdrawn therefrom or the glower is destroyed, and in the latter case another glower shall be automatically substituted as the active one. 'To accomplish this, two or more glowers are connected in parallel with each other and in series, with a proper restraining device for controlling the tlow of current therethrough. Owing to the fact that the conductivity of the glowerincreases with increasing temperature, that particular glower which offers the least resistance to the flow of current will, in the presence of the restraining device, rob the other glowers of current, and hence one only of the several which are connected in parallel will be operative. The same glower may or may not chance to be the operative one at each successive turning-on of the lamp, inasmuch as the selection of the particular glower through which the current shall flow depends largely upon the initial temperature given, other things being equal. It is possible, however, to so adjust the relative resistances and characteristics of several glowers as to cause them to become operative in a predetermined order of succession. In case a glower which. is operating shouldbreak orbecome destroyed the circuit may be automatically reestablished through one of the other or reserve glowers, and in this manner the practical life of a given lamp may be very great.

In the accompanying drawing I have illustrated diagrammatically the application of my invention.

Referring to the drawing, or a a a represent any desired number (in this instance four) of glowers of the character hereinbefore referred to and which are now known as the Nernst glower. These are composed of earth OXldS or mixtures thereoffor example, oxids of yttrium, thorium, zirconium, and other earth oxids having similar characteristics. A mixture of the oxid of yttrium and oxid of zirconium of German production in the proportions of thirty and seventy per cent. produces excellent results. The glowers are prepared by thoroughly mixing proper proportions of the oXids andformiugthem into a pasty mass by means of some suitable binding material'snch,for instance, as starch paste-- and then by means of molds or presses forming thin strips or threads,which are subsequently thoroughly baked. Proper lengths of these strips are then mounted between suitable supporting-wires b and b the ends being secured in any suitable manner-as, for instance, by being clamped and cemented by a paste of the same material as the glower, such paste being itself baked in position. The glowers thus constructed are connected in parallel, as shown in the drawing, the wires 1) being all connected with a conducting-support c, and

' fered by the resistance-wire to the flow of a greater current will be sufficient .to prevent any further increase of current. In case the wires L L are supplied with a constant-potential alternating current, either a resistance d of the character described or a suitable reactive coil may be employed, as found desirable. In either case this device acts to protect the glowers against an undue flow of current.

Any suitable means may be employed for imparting the preliminary heating to the gloW- ers and causing them to reach such a temperature as to become conductors when subjected to the normal difference of potential of the circuit. A convenient device consists of a coil eof platinum wire or othcrsuitable electric conductor placed in proper relation to I the glowers, so that when traversed by an electric current it will impart sufficient heat to the glowers to bring them to their conductive temperature. This coil 6 may be connected directly or indirectly in the circuit L L and may be automatically cut out of circuit when the current has been established through one of the glowers-as, for instance, by means of a switch 0', operated by a magnet 6 which is shown as being connected in series with the glowers. When the lamp is not in operation, the switch closes a shuntcircuit around the glowers from the conductor c to the conductor 0 through the coil 0.

When the circuit of the lamp is closed-as, forinstance,by a switch g-a current is caused to flow through the heating-coil e, and heat is imparted to the glowers. When any one of these glowers has become sufficiently cond uctive to permit the flow of current through itself, the current flowing through the coils of the magnet c will cause its armature to be attracted, and thus open the circuit through the heating-coil. The circuit will remain complete through the magnet and the steadying resistance 61 and the particular glower a, a 0. or a which has received current to the exclusion of the others. Thereafter the circuit will remain completed and the currentwill continue to flow through that particular glower until either the circuit is externally interrupted-as, for instance, by opening the key g or by the breaking of the glower. Thereupon the magnet will release its armature and the previous condition of the switch 0 will be reestablished, and if the circuit is still complete through the heating-coil another glower will be brought into operation in place of the one destroyed. In case two or more of the glowers shall simultaneously arrive at such a conductive condition as to be traversed by current when the lamp is first turned on, one of them by offering less resistance to the current than the others will re, ceive more current than the others, and thus offer a still better path for the flow of that current, and therefore ultimately receive all of the current flowing through the branch circuit to the exclusion of the other glowers. In some cases it may be desirable to connect the heating-circuit with the conductor leadin g to the magnet e as shown by dotted lines, so that the magnet shall not be traversed by the current passing to the heater. A resist ancef may be inserted for reducing the po* tential of the current applied to the terminals of the heater; Various other different ways of heating the glowers may be employed.

I do not limit myself to the particular means illustrated for carrying out my invention.

I claim as my invention 1. The combination of two or more glowers, whose conductivity increases within normal limits with increments of temperature, con nected in parallel with each other and a cur rent-restraining device connected in series therewith. v

2. The combination of two or more glowers composed of conductors of the second class connected in parallel with each other and a current-restraining device connected in series therewith.

3. The combination with a constant-poten tial electric circuit, of two or more glowers which are non-conductors when cold but conductors when hot having a negative temperature coefficient and a steadying resistance or reactive coil in series therewith.

4. The combination with two or more glowers composed of earth oxids and connected in parallel with each other, of a steadying resistance or reactive device connected in series therewith and means for giving said glowers an initial temperature sufficient to render one or more of the same conductive, substantially as described.

5. The combination with two or more glowers whose resistance decreases, Within limits, with increments of temperature, connected in parallel with each other, and a single heating device for simultaneously imparting heat to all of said glowers, and means for autooperation when a circuit has been established matically stopping the operation of said heatthrough one of the glowers and automatically ing device by the flow of current through any reinserting the heating device upon the cesone of said glowers. sation of current through all of said glowers. I 5 5 6. The combination With two or more glow- Signed by me at New York, N. Y., this 13th ers composed of earth oxids connected in parday of July, 1898. allel, means for simultaneously heating all of the same, an electric-current-restraining device connectedin series with the glowers and lVitnesses:

IO an electromagnetic circuit-controlling device J. H. JONES,

operating to cut out the heating device from L. (J. OARUANA.

CHARLES A. TERRY. 

